/*
 * Copyright (C) 1996-2001  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
 * INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
 * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
 * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
/*
 * Original code by Paul Vixie. "curlified" by Gisle Vanem.
 */

#include "setup.h"

#ifndef HAVE_INET_NTOP

#ifdef HAVE_SYS_PARAM_H
#include <sys/param.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
//#include <string.h>
//#include <errno.h>

#define _MPRINTF_REPLACE /* use our functions only */
#include <api/libcurl/mprintf.h>

#include "inet_ntop.h"

#define IN6ADDRSZ       16
#define INADDRSZ         4
#define INT16SZ          2

/*
 * Format an IPv4 address, more or less like inet_ntoa().
 *
 * Returns `dst' (as a const)
 * Note:
 *  - uses no statics
 *  - takes a unsigned char* not an in_addr as input
 */
static char *inet_ntop4 (const unsigned char *src, char *dst, size_t size)
{
	char tmp[sizeof "255.255.255.255"];
	size_t len;

	DEBUGASSERT(size >= 16);

	tmp[0] = '\0';
	(void)snprintf(tmp, sizeof(tmp), "%d.%d.%d.%d",
				   ((int)((unsigned char)src[0])) & 0xff,
				   ((int)((unsigned char)src[1])) & 0xff,
				   ((int)((unsigned char)src[2])) & 0xff,
				   ((int)((unsigned char)src[3])) & 0xff);

	len = strlen(tmp);
	if (len == 0 || len >= size)
	{
		SET_ERRNO(ENOSPC);
		return (NULL);
	}
	strcpy(dst, tmp);
	return dst;
}

#ifdef ENABLE_IPV6
/*
 * Convert IPv6 binary address into presentation (printable) format.
 */
static char *inet_ntop6 (const unsigned char *src, char *dst, size_t size)
{
	/*
	 * Note that int32_t and int16_t need only be "at least" large enough
	 * to contain a value of the specified size.  On some systems, like
	 * Crays, there is no such thing as an integer variable with 16 bits.
	 * Keep this in mind if you think this function should have been coded
	 * to use pointer overlays.  All the world's not a VAX.
	 */
	char tmp[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")];
	char *tp;
	struct
	{
		long base;
		long len;
	} best, cur;
	unsigned long words[IN6ADDRSZ / INT16SZ];
	int i;

	/* Preprocess:
	 *  Copy the input (bytewise) array into a wordwise array.
	 *  Find the longest run of 0x00's in src[] for :: shorthanding.
	 */
	MEMSET(words, '\0', sizeof(words));
	for (i = 0; i < IN6ADDRSZ; i++)
		words[i/2] |= (src[i] << ((1 - (i % 2)) << 3));

	best.base = -1;
	cur.base  = -1;
	best.len = 0;
	cur.len = 0;

	for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
	{
		if (words[i] == 0)
		{
			if (cur.base == -1)
				cur.base = i, cur.len = 1;
			else
				cur.len++;
		}
		else if (cur.base != -1)
		{
			if (best.base == -1 || cur.len > best.len)
				best = cur;
			cur.base = -1;
		}
	}
	if ((cur.base != -1) && (best.base == -1 || cur.len > best.len))
		best = cur;
	if (best.base != -1 && best.len < 2)
		best.base = -1;

	/* Format the result.
	 */
	tp = tmp;
	for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
	{
		/* Are we inside the best run of 0x00's?
		 */
		if (best.base != -1 && i >= best.base && i < (best.base + best.len))
		{
			if (i == best.base)
				*tp++ = ':';
			continue;
		}

		/* Are we following an initial run of 0x00s or any real hex?
		 */
		if (i != 0)
			*tp++ = ':';

		/* Is this address an encapsulated IPv4?
		 */
		if (i == 6 && best.base == 0 &&
				(best.len == 6 || (best.len == 5 && words[5] == 0xffff)))
		{
			if (!inet_ntop4(src + 12, tp, sizeof(tmp) - (tp - tmp)))
			{
				SET_ERRNO(ENOSPC);
				return (NULL);
			}
			tp += strlen(tp);
			break;
		}
		tp += snprintf(tp, 5, "%lx", words[i]);
	}

	/* Was it a trailing run of 0x00's?
	 */
	if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ))
		*tp++ = ':';
	*tp++ = '\0';

	/* Check for overflow, copy, and we're done.
	 */
	if ((size_t)(tp - tmp) > size)
	{
		SET_ERRNO(ENOSPC);
		return (NULL);
	}
	strcpy(dst, tmp);
	return dst;
}
#endif  /* ENABLE_IPV6 */

/*
 * Convert a network format address to presentation format.
 *
 * Returns pointer to presentation format address (`buf').
 * Returns NULL on error and errno set with the specific
 * error, EAFNOSUPPORT or ENOSPC.
 *
 * On Windows we store the error in the thread errno, not
 * in the winsock error code. This is to avoid loosing the
 * actual last winsock error. So use macro ERRNO to fetch the
 * errno this funtion sets when returning NULL, not SOCKERRNO.
 */
char *Curl_inet_ntop(int af, const void *src, char *buf, size_t size)
{
	switch (af)
	{
	case AF_INET:
		return inet_ntop4((const unsigned char*)src, buf, size);
#ifdef ENABLE_IPV6
	case AF_INET6:
		return inet_ntop6((const unsigned char*)src, buf, size);
#endif
	default:
		SET_ERRNO(EAFNOSUPPORT);
		return NULL;
	}
}
#endif  /* HAVE_INET_NTOP */
